Passive localization of microseismic events is commonly used to monitor resource extraction processes such as hydraulic fracture stimulation, or “fracking.” In a typical scenario, an array of geophones is positioned in a monitor well nearby the well undergoing treatment. The array records seismic energy released impulsively from induced failure events as fractures form. Arrival times and polarizations of P-waves and S-waves impinging the array, among other features, are used to estimate the location of each detected event. Additional information about the event, treatment, and seismic propagation environment is contained in the arriving waveforms. For example, the measure of seismic propagation loss, Q, may be estimated by analyzing the spectral content of arrivals as the wavefront propagates across the sensors of the array. Additionally, the event moment magnitude and its moment tensor may be estimated from arriving waveform features.
Co-pending U.S. patent application Ser. Nos. 13/598,580, 14/340,356 and 14/536,985, the contents of which are all incorporated by reference herein in their entirety, have dramatically advanced the state of the art by providing various techniques for analyzing and characterizing microseismic events utilizing sensor data such as data from an array of geophones as described above. However, certain challenges remain.